1. Field of the Invention
The present invention relates to a method and an apparatus of displaying a stereo model in a video game, a game apparatus and a computer-readable recording medium stored with a program of displaying a stereo model for a video game, for drawing a stereo model constituted by a plurality of polygons in a virtual three-dimensional space. Here, a stereo model designates 3D object constituted by a plurality of polygons.
2. Related Art
In recent years, by progress of display-related art, particularly computer graphics (CG) art, there have been produced more than before, games of three-dimensional images expressed more photorealistically. However, on the other hand, a new look has been taken at a game by images which are expressed non-photorealistically, that is, in a hand-writing tone and demand therefor is enhancing. As an example of such a non-photorealistic image, there is an image which is referred to as cel animation tone since the image resembles an image of cel animation produced by cel pictures.
Conventionally, in order to express a non-photorealistic game image in the cel animation tone, it is necessary to produce a character or a background image by handwriting, particularly, when a direction of displaying the character is changed in a game, an image in correspondence with each display direction is prepared by handwriting. In this way, a character image in cel animation tone is produced by manual labor and accordingly, only character images from limited directions have been prepared.
It is an object of the invention to provide a method and an apparatus of displaying a stereo model in a video game capable of displaying a character in a cel animation tone in an arbitrary direction in real time, a game apparatus and a computer-readable record medium stored with a stereo model display program for a video game.
In order to achieve the above-described object, according to a first aspect of the invention, there is provided a method of displaying a stereo model in a video game which is a method of displaying a stereo model in a video game for drawing the stereo model constituted by a plurality of polygons in a virtual three-dimensional space, the method comprising:
a first step of determining a direction of displaying the stereo model in response to an operation input;
a second step of arranging the stereo model and a contour drawing model having a shape of including the stereo model and constituted by a plurality of polygons in conformity with the direction determined at the first step such that a positional relationship in which the contour drawing model includes the stereo model is constituted; and
a third step of drawing the stereo model by reducing a gray scale number of a brightness previously given to the stereo model and drawing only the polygon of the contour drawing model in which a surface of the polygon is directed in a direction reverse to the direction determined at the first step. In this case, xe2x80x9ca direction of displaying the stereo modelxe2x80x9d is, for example, a direction from the stereo model to a view point. Further, xe2x80x9csurfacexe2x80x9d mentioned above, is a face of the stereo model directed to an outer side. By executing such a method, the stereo model in a cel animation tone is drawn.
According to the invention, the direction of displaying the stereo model is determined in response to the operation input and the stereo model is drawn in the cel animation tone in accordance with the determined direction. Thereby, even in the direction of displaying the stereo model is changed by the operation input, the stereo model from the changed direction can be drawn in the cel animation tone in real time.
According to the method of displaying a stereo model in a video game, the third step may be constituted by a step of drawing the stereo model by reducing the gray scale number of the brightness previously given to the stereo model and drawing only the polygon of the contour drawing model in which the surface of the polygon is directed in the direction reverse to the direction determined at the first step by using a predetermined color.
According to the method of displaying a stereo model in a video game, the first step may be constituted by a step of moving the stereo model and determining the direction of displaying the stereo model in response to the operation input.
According to the method of displaying a stereo model in a video game, the first step may be constituted by a step of switching a view point and determining the direction of displaying the stereo model in response to the operation input.
According to the method of displaying a stereo model in a video game, the stereo model may be a character.
Further, according to a second aspect of the invention, there is provided a computer-readable record medium which is a computer-readable record medium stored with a stereo model display program for a video game for drawing a stereo model constituted by a plurality of polygons in a virtual three-dimensional space:
wherein the stereo model display program makes the computer execute:
a first step of determining a direction of displaying the stereo model in response to an operation input;
a second step of arranging the stereo model and a contour drawing model having a shape of including the stereo model and constituted by a plurality of polygons in conformity with the direction determined at the first step such that a positional relationship in which the contour drawing model includes the stereo model is constituted; and
a third step of drawing the stereo model by reducing a gray scale number of a brightness previously given to the stereo model and drawing only the polygon of the contour drawing model in which a surface of the polygon is directed in a direction reverse to the direction determined at the first step.
According to the program, the third step may be constituted by a step of drawing the stereo model by reducing the gray scale number of the brightness previously given to the stereo model and drawing only the polygon of the contour drawing model in which the surface of the polygon is directed in the direction reverse to the direction determined at the first step by using a predetermined color.
According to the program, the first step may be constituted by a step of moving the stereo model and determining the direction of displaying the stereo model in response to the operation input.
According to the program, the first step may be constituted by a step of switching a view point and determining the direction of displaying the stereo model in response to the operation input.
According to the program, the stereo model may be a character.
Further, the program according to the second aspect of the invention is stored in a record medium of, for example, CD-ROM, floppy disk, memory cartridge, memory, hard disk or the like or a storing apparatus. By making a computer read the program stored in a record medium or a storing apparatus in this way, an apparatus of displaying a stereo model and a game apparatus, mentioned below, can be realized. Further, the program can be easily distributed and sold independent from an apparatus as a software product by a record medium. Further, by executing the program by using a hardware such as a computer, the graphics technology of the invention can easily be executed by the hardware.
Further, according to a third aspect of the invention, there is provided an apparatus of displaying a stereo model in a video game which is an apparatus of displaying a stereo model in a video game for drawing a stereo model constituted by a plurality of polygons in a virtual three-dimensional space, wherein the apparatus executes:
determining a direction of displaying the stereo model in response to an operation input;
arranging the stereo model and a contour drawing model having a shape of including the stereo model and constituted by a plurality of polygons in conformity with the determined direction such that a positional relationship in which the contour drawing model includes the stereo model is constituted; and
drawing the stereo model by reducing a gray scale number of a brightness previously given to the stereo model and drawing only the polygon of the contour drawing mode in which a surface of the polygon is directed in a direction reverse to the determined direction.
By making a computer execute the respective steps by the method of displaying a stereo model according to a first mode of the invention, an effect similar to that in the method of displaying a stereo model, mentioned above, can be achieved.
Therefore, by executing the described processing steps by using a hardware of a computer or the like, the stereo model display technology of the invention can easily be executed by the hardware.
Further, according to a fourth aspect of the invention, there is provided a game apparatus which is a game apparatus for drawing a stereo model constituted by a plurality of polygons in a virtual three-dimensional space, the apparatus comprising:
a computer;
a computer-readable record medium stored with a program which the computer is made to execute;
wherein the program makes the computer execute:
a determining processing of determining a direction of displaying the stereo model in response to an operation input;
an arranging processing of arranging the stereo model and a contour drawing model having a shape of including the stereo model and constituted by a plurality of polygons in conformity with the direction determined by the determining processing such that a positional relationship in which the contour drawing model includes the stereo model is constituted; and
a drawing processing of drawing the stereo model by reducing a gray scale number of a brightness previously given to the stereo model and drawing only the polygon of the contour drawing model in which a surface of the polygon is directed to a direction reverse to the direction determined by the determining processing.